Assessment of the selenium status in cattle herds in Wallonia

The selenium content is low in the soil of Wallonia, the southern part of Belgium. It is therefore logical that the selenium content in feedstuffs grown in these fields-grass, conserved forages, cereals and by-products- is also low. A survey was carried on 166 farms in Wallonia. The farms were located in 4 specific agronomy areas- Pays de Herve with mainly pastures (4farms)- Ardennes (a sub-mountainous area and pastures, 24 farms), Hesbays with mainly arable lands (55 farms) and Condroz with both pastures and arable (83 farms)
There were herds with dairy cow, herds with beef cow and herds with both types of animals. The average age was 44±15 months for the cows and 18±6 months for the heifers. The blood samples were taken on five healthy animals of each herd, on the end of the winter just before the animals went to pastures. The selenium status was assessed by the activity of the Glutathion peroydase. The selenium status was extremely variable for the different farms of the 4 areas with variation coefficient of 56%. It was in Pays de Herve and in Hesbaye that the average selenium status was the highest at 53 and 56 µg Se/l. By contrast, it was in Ardenne and in Condroz that the status was the lowest, at 39 and 43 µg Se/l. The selenium status was, on the whole, higher in the dairy herds than in the beef herds owing to the higher selenium provision by the mineral mixtures and the compound feedstuffs added to the diet.
Assuming that the normal selenium concentration in plasma being 70µg/l, it appeared also that 81% of the individual animals tested were below the normal Se concentration. It can thus be concluded from the present survey that the cattle herds in Wallonia are deficient in selenium.